This invention relates to compositions for retarding the flammability of polyester articles which can be used in the form of a stable aqueous emulsion. This invention also relates to flame retardant polyester articles and the method for the production of the same.
It is known that compounds containing halogen or phosphorus are used as flame retarding agents for polyester fiber or film. For the flame retarding treatment of polyester, there are known two different typical methods. One is to improve the flame retardancy of raw materials for polyester and the other is to subject polyester articles such as fibers and films to a flame retarding treatment. In the latter case, a halogenated phosphoric ester; e.q. tris (2,3-dibromopropyl) phosphate is preferably used by the exhaustion from an aqueous dispersion, the so-called thermosol method or so-called carrier method. With any of these conventional methods, however, it has been difficult to impart to polyester articles a sufficient flame retardancy which is one of the properties of the above mentioned halogenated phosphoric ester. Especially, in the method of exhaustion from an aqueous dispersion it is necessary to prepare, for a treating bath, an emulsion of a hydrophobic compound such as tris (2,3-dibromopropyl) phosphate by the aid of a proper emulsifier. It is also required to obtain a homogeneous and stable emulsion for the purpose of uniform treatment of polyester fiber or film with a fire retarding agent. However, in many cases the flame retarding agents are degraded by the addition of conventional emulsifiers. It is considered that this is partly due to the properties of the emulsifiers per se and partly depends on the amount of the emulsifiers used. For example, in the case of emulsification of tris (2,3-dibromopropyl) phosphate with higher fatty acid- ethylene oxide adduct which is known as a favorable emulsifier therefor, the flame retarding ability of tris(2,3-dibromopropyl) phosphate is greatly reduced in accordance with an increase in the amount of the emulsifier as shown in the following table. Consequently, a satisfactory flame retarding effect can hardly be expected if a stable emulsion is used for the purpose of uniform application of the flame retarding agent to the polyester article.
______________________________________ Amount of Concentration emulsifier % of TDPP in a by weight Stability of Oxygen Index bath % by (based on emulsion in (JIS-K-7201 weight TDPP) a bath 1972) ______________________________________ 15 -- -- 31.5 15 5 bad 27.0 15 7.5 " 26.5 15 10 " 26.5 15 20 good 25.0 Untreated cloth 23.5 ______________________________________ TDPP: tris (2,3-dibromopropyl) phosphate Emulsifier: polyethylene glycol stearyl ether Cloth to be treated: polyester taffeta
The principal object of the invention is therefore to provide a new and improved flame retardant composition for polyester which can be used in the form of a stable emulsion without sacrificing the good flame retardancy of halogenated phosphoric ester.
The other objects and advantages of the invention will become clear from the following detailed description of the invention.